Textile bleaching composition



United States Patent Office 3,%l,550 Patented Oct. 30, 1962 3,061,550 TEXTILE BLEACHING CGMPOSITION Melvin Myron Baevsky, Wilmington, Del., assignor to E. I. du Pont de Nernours and Company, Wilmington, DeL, a corporation of Delaware No Drawing. Filed May 11, 1959, Ser. No. 812,135. 6 Claims. (Cl. 252-99) This invention relates to compositions of matter which are useful for the bleaching of textiles and other materials, particularly those made of the synthetic linear polyamides known as nylon.

The bleaching of nylon materials, especially textile materials which are to be used in the white or undyed state, has presented a problem which has not been heretofore satisfactorily solved. U-ndyed nylon fabrics which have been used for some time may become slightly yellow or otherwise discolored. The use of alkaline peroxide bleach solutions results in excessive damage to nylon fabrics, while other bleaching compositions which have been proposed are either not sufficiently effective or are very inconvenient to use. The use of hydrogen peroxide in mildly acidic solutions, as described in US. 2,720,441, requires an excessive length of time for bleaching, while its use in strongly acidic solutions leads to excessive strength losses. The most effective bleach available heretofore has included alkali metal hypochlorites and acetic acid. This method of bleaching, however, is inconvenient and the results are dependent on accurate measurement of the ingredients in home laundering. Thus, the lack of a convenient and eflective home bleach for nylon reduces the potential of nylon in several of the larger markets for white goods and also in the full utilization of nylon in many of its present end uses, such as end blends with cotton.

It is accordingly an object of this invention to provide an improved bleaching composition. Another object is to provide a composition of matter which may be conveniently and effectively used for home bleaching of nylon textile materials. A further object is to provide a bleach ing composition which may be used in conjunction with soaps and detergents which are commonly used in home laundering of nylon and other textiles.

The above objects are accomplished according to this invention by a bleaching composition comprising a solid, stable peroxygen compound and an N-acylimide having the general formula:

wherein R is aromatic or substituted aromatic and R is an imide radical, preferably derived from a cyclic imide.

The above compositions are superior to any presently available home bleach for nylon in that they are highly effective in removing discoloration from nylon fabrics without causing excessive strength losses, and in that they may be conveniently and efiectively used alone or in combination with household soaps or detergents for bleaching purposes. 7

Although it has been customary to judge fabric color by eye, it is much more satisfactory to use precise instrumental methods whereby a numerical value can be obtained. In the following examples, color measurements are made using a differential colorimeter as described by L. B. Glasser and D. I. Troy in the Journal of the Optical Society 42, 652660 (1952). These authors describe a method whereby reflectance measurements can be converted into the color coordinates, L for lightness, a for greenesS-redness, and b for yellowness-blueness.

Using this system, negative values of b representv blue shades, while positive values represent yellow shades. The depth or intensity of color will be proporfabrics before discoloration.

tional to the numerical magnitude of the b value. Also described is a method for determining the total color difference (AE) between a sample and a white standard when the sample contains an admixture of colors which cannot be described in terms of any single color coordinate.

In the following examples, bleaching tests are carried out on fabrics which have been discolored by either dye transfer or heat yellowing, since these are the most common sources of garment discoloration encountered in actual use. The dye transferred fabrics are discolored by laundering white fabrics in the presence of blue, red, and yellow fabrics which had been dyed to saturation with certain dyes of poor washfastness. The fabrics used for this purpose in the following examples are dyed with a'blue dye, Anthraquinone Blue SWF (Prototype No. 12, Technical Manual and Yearbook, A.A.T.C.C., 1955), a red dye, Celanthrene Red 3BN (Prototype No. 234), and a yellow dye, Celanthrene Fast Yellow GL (Prototype No. 534). The color of the dye transferred fabrics is numerically described in the examples in terms of the total color difference (AB) when compared to the same Thus, the lower the total color difference (AE), after treatment with an oxidizing agent, the greater the color removal and the more effective the bleach. The heat-yellowed fabrics described in the following examples are discolored by exposure to excessive heat. The color of these fabrics is described in terms of the +b value (yellowness). The effectiveness of the bleaching action of the various compounds given in the examples can be clearly determined by comparison of the magnitude of the +b values of a fabric, before and after bleaching.

EXAMPLE I N-benzoyl succinimide and anhydrous sodium perborate' is added to the bath and the fabrics allowed to soak for one hour at a temperature of 45 C. The fabric samples are then removed from the bath, rinsed and dried, and the total color (delta E) of the samples before and after bleaching is determined with a differential colorimeter as described above. Table I below shows the results obtained with various molar ratios of sodium perborate to N-benzoyl succinimide and with various concentrations of the bleaching composition. The concentration of bleaching composition is expressed as percent based on the weight of the fabric sample. Total color measurements before and after bleaching are shown for Table I Concentra- AE tion, Per- 7 cent Molar Ratio I Before After When the buffering agents, citric acid and disodium phosphate, are mixed with the dry bleaching composition and the weight of bleaching composition increased sufficiently to provide the same concentration of N-benzoyl succinimide and sodium perborate in the bleaching lauryl sulfate) and 0.26% by weight of a commercial fluorescent whitening agent. Nylon taffeta fabric samples are bleached with this composition, using the conditions given in Example Iexcept that sufficient bleach bath, similar results are obtained. 5 is added to the bath to give a concentration of 1.0%, based on the weight of the fabric sample. The total EXAMPLE H color of the samples is determined before and after Samples of nylon taffeta fabric are treated as described bl hi as d ib d i Example I, T bl V b l in Example I except that Various Nfiuhstitllted lfIlldeS shows results obtained with the freshly prepared bleachwere substituted for N-benzoyl succinimide. Table II ing composition and after storage for six and ten Weeks below Shows the compounds used, the molar ratio of in both glass containers and cardboard cartons. As hydrous Sodium pefhofate t0 imide and the total 60101 shown in the table, no substantial loss in bleaching power before and after bleaching. A sufficient amount of the is observed. bleach composition is added to give a concentration in th fabrc gzlcnliflgase of 0 34%, based on the weight of e 1 Table V Table 11 M 1 AE B to e Aft G 1 er na tiii B A More er Fresh bleaching composition 13. 8 1. 8 iger goweekli stigragg in glass... g g e 4. er wee ssora ein ass 13-21fiii zgh h g l li inimide 9.2 After 6 weeks storage in c rdboardfl 13. 8 3. 3 N -beta-naphthoylsuccinimide 7. 5 9,4 27 4 Af er 10 Weeks storage in cardboard 13. 8 3. 3 N-benzoylglutarimide. 6.4 8.5 4.1 N-p-ch]orobenzoylsuocinimide 7. 0 14. 5 7. 2

T l E Z F bl h d f EXAMPLE v1 1 a on i i g 2 o fig i ggi gg i i iii; g fi 30 This example illustrates the efiectiveness of the bleachadded a mixuire of Ndbenzoyl 5 dimgthylhy dant01-n ing compositions of this invention at various concentraand sodium perborate, the total weight of the bleaching Hons and Y molar ratlos of peroxygen compomld bath being 100 times the Weight of the sample The to N-substituted 1rn1de. Samples of nylon taffeta fabric bleach bath is maintained at a pH of 6.7 by the addition f bleached hour at 45 infaqueous i of citric acid and disodiumphosphate. Table III shows mg bath contamlilg N'benzoyl p i and sodium the reduction in color obtained with various concentraz g the welght of bath belpg 50 the Welght tions of N-benzoyl 5,5-dimethylhydantoin based on the f 3 The concentration of N'benzoyl i weight of the fabric and various molor ratios of sodium cmlml e 15 .kept Constant based Weight Perborate to N benzoyl dimethylhydantom 40 of the fabric sample, while the molar ratio of SOdIUlTl perborate to N-benzoyl succinimide is varied as shown Table III in Table VI below. The pH of the bleach bath is varied by changing the relative concentration of the buffers. I For pH 6 and 7, a citric acid-disodium phosphate buffer is Concentmhon Percent used, while for pH 8 and 9, a boric acid-sodium hydroxide Bef After buffer is employed to give the values shown below. The reduction in total color and yellowness (-l-b) at various m g5 L7 pH levels and various molar ratios is shown in Table 3:2 3:? {g VI-A below. Table VI-B shows the reduction in total 1.4 8.5 1.0 color and yellowness obtained with various concentrations of N-benzoyl succinimide and various molar ratios of EXAMPLE IV sodium perborate to N-benzoyl succinimide when the Example I is repeated except that potassium mono aqueous bleaching bath is maintained at a pH of 10. persulfate, KHSO is substituted for sodium perborate. Table IV below shows the molar ratio of potassium monopersulfate to N-benzoyl succinimide in the bleach- Table ing composition, the concentration of the bleaching composltlon based on the weight of the fabric and the total DH Molar AE yellowness color before and after bleaching. Ratio Table IV 18. 4 7. 2 1.0 6.5 4.6

Molar Ratio tiiiii f e r AE 0 4 3 cent l8 2'2 it Before After 0 3 6 EXAMPLE V V 610 1014 31s A bleaching composition is prepared by mixing 24.9% iii 2:; by weight of N-benzoyl succinimide, 39.0% by weight of 2-2 2' anhydrous sodium perborate, 33.3% by weight of citric 6:0 16:8 5:?

acid, 2.54% by weight of an anionic detergent (sodium Table VI-B Concentration of N-benzoyl Molar Total Yellowness succinimide, percent Ratio Color EXAMPLE Vll A bleaching composition is prepared by mixing 42% by weight of N-benzoyl succinimide, 12.5% by weight of sodium perborate, 42.5% by weight of sodium carbonate, 2.6% by weight of a detergent (sodium l auryl' sulfate) and 0.4% of a fluorescent whitener (Tinopal RBS). Swatches (6 x 6 inches) cut from a heat-yellowed commercial cotton percale sheet are bleached in a solution to which has been added 1% (based on fabric weight) of the above bleach composition for one hour at 45 C. Colorimeter analysis showed the original fabric to have a yellowness value of 0.3 unit, which is increased to 3.5 units after exposure to heat. After bleaching, the fabrics have a yellowness value of 0.4 unit. Measurement of the fluidity of the sample, which is a measure of the extent of degradation due to bleaching, using test method 82-54 of the Technical Manual and Year Book of the American Association of Textile Chemists and Colorists, showed no appreciable change after three bleaching cycles. When the same fabric was bleached with alkali-chlorite'and vinegar, the fluidity after one bleaching increased markedly and after three bleachings was up to a value of 20.2,

as compared to 3.7 for the bleaching composition of this invention.

EXAMPLE VIII Example VII is repeated using the bleaching composition of Example V with substantially the same results. A Wide range of pH values can be used in bleaching fabrics with the compositions of this invention without appreciable damage to the fabrics. The desired pH may be achieved by adding suitable well-known buffering agents to the bleaching solution or by mixing the buffering agents with the bleaching composition in the dry state, if desired. The bleaching efiectiveness of these compositions at high'pH values permits their use in combination With common household laundry soaps and detergents for preventive bleaching of nylon and other fibers. Likewise, almost any of the commercially available optical whiteners may be used in combination with these compositions. At a pH in the range of about 6 to about 10, the bleach is most efiective and fiber degradation is minimized considerably.

Preferably, the bleaching composition comprises N- benzoyl succinimide and sodium perborate, either anhydrous or hydrated, since this composition is highly effective and the ingredients are readily available and relatively inexpensive.

Suitable N-acylimides, in addition to those givenin the examples, include: N,N-dibenzoylformamide, N,N-dibenzoyl acetamide, 1,3-dibenzoyl dimethylhydantoin, N-benzoylphthalimide, N-benzoylpyrrolidone, N-cinnamoylsuccinimide, and N m nitrobenzoylsuccinimide. Preferably, cyclic N-substituted irnides are employed. R in the formula ll R-C-Ri I is preferably an aromatic or substituted aromatic radical,

aliphatic radicals being much less eiiective.

Any pcroxygen compound which is stable in the dry state and which liberates active oxygen readily when dissolved in aqueous media may be employed. Suitable pcroxygen compounds, in addition to those given in the examples, include alkali percarbonates such as sodium and potassium percarbonate, urea peroxide, Zinc peroxide, calcium peroxide, magnesium peroxide, tetrasodium pyroperphosphate, and disodium perphosphate and others.

The molar ratio of pcroxygen compound to N-acylimide may vary widely depending on the conditions employed. As little as 0.1 mol of peroxygen compound per mol of N-acylimide is efiective, while as much as '12 mols of pcroxygen compound per mol of 'N-acylimide is not harmful at the lower pH levels. However, when the bleach composition is used at high pH values, e.g., pH 10, the molar ratio is preferably no higher than about 2 for optimum bleaching.

The bleaching compositions of this invention are particularly suitable for bleaching nylon textiles but may also be used for bleaching cotton, regenerated cellulose, and textile materials made from various synthetic fibers such as polyesters, polyacrylonitrile and polyurethane fibers.

The concentration of the bleaching composition in an aqueous solution, as well as the time and temperature involved, may be adjusted according to the particular use anticipated. For example, as a preventive bleach to be used during laundering of nylon fabrics to prevent the build-up of discoloration, a concentration between about 0.02 and about 0.2%, based on the Weight of solution, is satisfactory. For the latter use, an average Washing cycle (10 -20 minutes) of a home automatic washing machine using water at a temperature of about 30 to about 60 C.,' is satisfactory. As a corrective bleach to whiten badly discolored fabrics, a concentration of about 0.1 to about 2.0%, based on the weight of solution, with a washing cycle of about 20 to about 60 minutes with water at about 30 to about C., is satisfactory.

I claim:

1. A textile bleaching composition consisting essentially of a solid, stable pcroxygen compound and a water soluble N-acylimide having the general formula:

n R-O-Ih wherein R comprises an aromatic group and R comprises an imide radical, the molar ratio of the pcroxygen compound to imide being in the range of from about 0.1 to about 12.4.

2. The bleaching composition of claim 1 wherein the pcroxygen compound is sodium perborate.

3. The bleaching composition of claim 1 wherein the N-acylirnide is N-benzoyl succinimide.

4. A textile bleaching composition consisting essentially of sodium perborate and N-benzoyl succinimide in a molar ratio of from about 0.1 to about 12.4.

5. The bleaching composition of claim 4 in aqueous solution, said solution containing at least about 0.1% by weight thereof.

6. The bleaching solution of claim 5 buffered to a pH of 6-10.

References Cited in the file of this patent UNITED STATES PATENTS 825,883 Heinrici July 10, 1906 2,717,878 Malkemus Sept. 13, 1955 2,898,181 Dithmar et al Aug. 4, 1959 FOREIGN PATENTS 16,151 Great Britain Jan. 4, 1906 782,898 Great Britain Sept. 18, 1957 

1. A TEXTILE BLEACHING COMPOSITION CONSISTING ESSENTIALLY OF A SOLID, STABLE PEROXYGEN COMPOUND AND A WATER SOLUBLE N- ACYLIMIDE HAVING THE GENERAL FORMULA: 